Public bug reported:
[Kernel Regression] Backlight control stops working and missing initrd
on kernel 7.0.0-28-generic (Acer Nitro V 15 / RTX Graphics)
Description:
Environment:
Device: Acer Nitro V 15
GPU: NVIDIA GeForce RTX / Intel or AMD iGPU (Hybrid Graphics)
OS: Ubuntu 24.04 LTS
Affected Kernel: linux-image-7.0.0-28-generic
Working Kernel: linux-image-6.17.0-40-generic
Description of the Issue:
After updating to linux-image-7.0.0-28-generic, two main issues occurred
on the Acer Nitro V 15:
Kernel Panic on Boot (Missing initrd):
Upon initial boot after upgrade, the system threw a Kernel Panic error:
VFS: Unable to mount root fs on unknown-block(0,0)
Root Cause: The initrd.img-7.0.0-28-generic image was not automatically
generated during the kernel installation. Running sudo update-initramfs
-c -k 7.0.0-28-generic and sudo update-grub resolved the boot issue, but
led to the second problem below.
Display Backlight Control Broken (Regression):
Once booted into 7.0.0-28-generic, display brightness adjustment stopped
working completely.
Adjusting the brightness slider in GNOME Settings or using hardware FN
shortcut keys moves the UI brightness bar normally, but the physical
screen backlight level remains static at full brightness.
This appears to be an ACPI / GPU driver regression affecting the
backlight interface on hybrid graphics hardware (NVIDIA RTX + iGPU)
introduced in kernel 7.0.0-28.
Steps to Reproduce:
Boot into linux-image-7.0.0-28-generic on Acer Nitro V 15.
Try adjusting screen brightness via GNOME System Menu slider or Keyboard
Brightness keys.
Observe that the UI slider changes, but the physical screen brightness
stays unchanged.
Expected Behavior:
Screen backlight intensity should adjust dynamically according to the slider
and keyboard inputs.
Workaround / Current Status:
Booting back into kernel 6.17.0-40-generic completely fixes the brightness
control issue, confirming this is a regression in kernel 7.0.0-28.
ProblemType: Package
DistroRelease: Ubuntu 24.04
Package: linux-image-7.0.0-28-generic 7.0.0-28.28~24.04.1
ProcVersionSignature: Ubuntu 6.17.0-40.40~24.04.1-generic 6.17.13
Uname: Linux 6.17.0-40-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.28.2-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC1: jonatas-alves 2680 F.... pipewire
jonatas-alves 2686 F.... wireplumber
/dev/snd/controlC0: jonatas-alves 2686 F.... wireplumber
/dev/snd/seq: jonatas-alves 2680 F.... pipewire
CRDA: N/A
CasperMD5CheckResult: pass
Date: Thu Jul 23 10:40:06 2026
ErrorMessage: o subprocesso instalado, do pacote linux-image-7.0.0-28-generic,
o script pre-removal retornou erro do status de saída 1
InstallationDate: Installed on 2026-03-23 (122 days ago)
InstallationMedia: Ubuntu 24.04.4 LTS "Noble Numbat" - Release amd64 (20260210)
MachineType: Acer Nitro ANV15-51
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.17.0-40-generic
root=UUID=b55a3bee-ba43-4226-bb15-6ba73a33edea ro quiet splash vt.handoff=7
Python3Details: /usr/bin/python3.12, Python 3.12.3, python3-minimal,
3.12.3-0ubuntu2.1
PythonDetails: N/A
RelatedPackageVersions: grub-pc N/A
SourcePackage: linux-hwe-7.0
Title: package linux-image-7.0.0-28-generic 7.0.0-28.28~24.04.1 failed to
install/upgrade: o subprocesso instalado, do pacote
linux-image-7.0.0-28-generic, o script pre-removal retornou erro do status de
saída 1
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/21/2025
dmi.bios.release: 1.26
dmi.bios.vendor: INSYDE Corp.
dmi.bios.version: V1.26
dmi.board.asset.tag: Type2 - Board Asset Tag
dmi.board.name: Sportage_RTH
dmi.board.vendor: RPL
dmi.board.version: V1.26
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: Chassis Version
dmi.ec.firmware.release: 1.6
dmi.modalias:
dmi:bvnINSYDECorp.:bvrV1.26:bd03/21/2025:br1.26:efr1.6:svnAcer:pnNitroANV15-51:pvrV1.26:rvnRPL:rnSportage_RTH:rvrV1.26:cvnAcer:ct10:cvrChassisVersion:sku0000000000000000:
dmi.product.family: Acer Nitro V 15
dmi.product.name: Nitro ANV15-51
dmi.product.sku: 0000000000000000
dmi.product.version: V1.26
dmi.sys.vendor: Acer
** Affects: linux-hwe-7.0 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-package noble
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https://bugs.launchpad.net/bugs/2161643
Title:
Kernel 7.0.0-28 Regression on Acer Nitro V 15 (RTX)
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